小尺度通道多孔介质表面火焰边界的实验研究

Experimental Investigation for Boundary of Surface-Stabilized Flame on a Porous Media in a Mesoscale Channel

关键词:  小尺度燃烧  多孔介质  表面火焰  预混燃烧  环形通道  实验研究

Key words:  Mesoscale combustion  Porous media  Surface-stabilized flame  Premixed combustion  Annular channel  Experimental investigation

摘要:

为了更好地在小尺度燃烧室中组织燃烧，对小尺度环形通道内多孔介质表面甲烷与空气预混火焰开展了流量和雷诺数边界特性实验研究。多孔介质采用了烧结金属粉末材料，燃烧在石英玻璃管和不锈钢管以及多孔介质组成的小尺度环形通道中进行。研究结果表明:随着预混气流量的增加，环形通道内的火焰形态由多孔介质表面火焰向推举火焰衍变，与推举火焰相比，多孔介质表面火焰更适合于在微小型燃烧室内组织燃烧。稳态预混气温度随流量的增加先上升后下降，其流量范围与两个火焰形态的基本重合，可以将温度的转折点作为表面火焰边界的定量判据。对于多孔介质表面火焰流量边界而言，当量比小于1.0时，甲烷预混气的表面火焰流量边界随着当量比的增大逐渐变宽；当量比大于1.0时，随着当量比的增大，多孔介质表面火焰流量边界变窄。对于多孔介质表面火焰雷诺数边界而言，随着当量比的增大，雷诺数边界逐渐变宽。

Abstract:

To achieve well-organized combustion in mesoscale combustors，the mass flow and Reynold boundary of surface-stabilized flame on a porous media in an annular mesoscale channel was studied experimentally with methane-air premixture. The porous media is composed of sintered metal powder. The combustion was carried out in the mesoscale annular channel formed by a quartz glass tube，a stainless steel tube and the porous media. The experimental results indicate that the flame in the annular channel evolves from surface-stabilized flame on the porous media to lift-off flame in the channel with the increasing mass flow of the premixed gas. Compared with the lift-off flame，the surface-stabilized flame on the porous media is more suitable for the mesoscale combustion. The steady temperature of the premixed gas drops after the first rise with the increasing flow of the premixed gas. The flow range concides with that of the two flame shapes on the whole，so the turning point of the temperature is adopted as the quantitative criterion for the flow boundary of the surface-stabilized flame. As to the mass flow boundary of the surface-stabilized flame on the porous media，when the equivalent ratio is less than 1.0，the boundary is gradually widened with increasing equivalent ratio. When the equivalent ratio is greater than 1.0，the boundary is narrowed with increasing equivalent ratio. As for the Reynold boundary of the surface-stabilized flame on the porous media，the boundary is gradually widened with increasing equivalent ratio.